As noted here, I've been learning Rav Kook's Orot haTeshuvah in Elul.
Drawing on sources from Tanach, Gemara and Kabbalah, Rav Avraham Yitzchak haKohen Kook taught that teshuvah is more than a mechanical, three-step method of admitting, correcting and abandoning our sins. As Rav Kook described it, Teshuvah is a glittering thread woven into the fabric of the universe, a natural longing for righteousness, and an engine inexorably moving all of Creation toward the original Divine vision of perfection.
Here are several key passages from Orot haTeshuvah, Rav Kook’s landmark work describing the nature of Teshuvah. The translation is almost linear; the original Hebrew is available at http://www.hebrewbooks.org/31307.
Teshuvah is guaranteed:
The world is guaranteed to come to full repentance. The world is not static; it continues to develop. True, complete development must bring about total physical and spiritual health, which will bring with it the light of the life of teshuvah. (Orot haTeshuvah 5:3)
Teshuvah comes from the longing of the entire universe to become better and more pure, stronger and more elevated than its current state. At the core of this drive is a life-force that triumphs over the limited, weak character of natural existence. The repentance of an individual, and certainly of the community, draws its strength from this life-force, which flows unceasingly, at full strength. (Orot haTeshuvah 6:1)
Teshuvah always resides in the heart; even at the moment of sin, the impulse for teshuvah is hidden in the soul, radiating influence which will be revealed later, with the arrival of the regret that calls for teshuvah. Teshuvah resides in the depths of existential life, for it preceded the universe, and before sin arrives its teshuvah is already prepared. Therefore, nothing in this universe is as certain as teshuvah, and, ultimately, all will be repaired. (Orot haTeshuvah 6:2)
Teshuvah is a natural product of health and maturity:
The desire for teshuvah is a person’s most healthy spiritual desire. A healthy soul in a healthy body is compelled to achieve the great bliss of teshuvah, experiencing in it the greatest natural pleasure.
A properly functioning body removes harmful materials, thereby improving and healing the body. One who is spiritually and physically healthy will remove evil deeds and the evil, corrupt impressions they produce, every evil thought, and the distance from Divine influence which founds all evil, crudeness and ugliness. (Orot haTeshuvah 5:1)
Teshuvah is a process of developing our potential:
A person’s life is perfected by developing his inherent character. However, one’s still-undeveloped character lacks insight, and so sin is guaranteed along this path of development. “There is no righteous person in the land who will commit good and not sin. [Kohelet 7:20]” On the other hand, eliminating one’s natural character in order to prevent sin is itself the greatest sin, [regarding which the Torah says of the nazir in Bamidbar 6:11,] “He shall atone for his sin against life.”
Therefore, Teshuvah repairs one’s corruption and restores the world and this person’s life to its root, specifically by helping the inherent character to develop. (Orot haTeshuvah 5:6)
The potential for Teshuvah is always present:
Even if a person consistently stumbles, damaging his righteousness and ethical behavior, this does not damage his fundamental perfection. A person’s fundamental perfection is found in his longing and desire to achieve perfection, a desire which is the foundation of teshuvah, and which continually governs his path in life. (Orot haTeshuvah 5:5)
The rewards of Teshuvah:
With every aspect of ugliness banished from a person’s soul upon his internal commitment to teshuvah, whole worlds are revealed, in celestial clarity, in the midst of his soul. Removal of sin is like removal of a blinder from above an eye, such that the full field of vision is now revealed, a light from the breadth of heaven, earth and all they contain. (Orot haTeshuvah 5:2)